Auditory brain-stem responses (ABRs) in sleep respiratory disorders

Area of Science:

• Neuroscience
• Sleep Medicine
• Audiology

Background:

• Neurophysiological effects of sleep respiratory disorders (SRDs) are not fully understood.
• SRDs are known to disrupt auditory event-related potentials, specifically delaying P300 cognitive potentials.
• Auditory Brainstem Responses (ABRs) assess auditory brainstem structures, independent of cognitive function.

Purpose of the Study:

• To evaluate the neurological impact of SRDs on the central nervous system using ABRs.
• To differentiate the effects of sleep apnoea syndrome (SAS) versus SAS combined with respiratory insufficiency (SAI) on auditory pathways.

Main Methods:

• Four patient groups were studied: snorers (S), sleep apnoea syndrome (SAS), sleep apnoea with respiratory insufficiency (SAI), and respiratory insufficiency alone (RI).
• Standard polysomnography was performed, including quantitative analysis of sleep, respiratory events, and oxygen saturation.
• ABRs were recorded, and interpeak latencies (IPLI-III, IPLIII-V, IPLI-V) were measured to assess central conduction time.

Main Results:

• ABR interpeak latencies were within normal ranges for all groups.
• Significant differences in ABR latencies were found between groups (ANOVA).
• Patients with SAI exhibited longer IPLIII-V and IPLI-V compared to patients with SAS alone, indicating slower central conduction time.

Conclusions:

• Sleep apnoea syndrome alone does not appear to affect lower brainstem auditory function.
• The combination of sleep apnoea syndrome and respiratory insufficiency is associated with delayed central auditory conduction.
• The observed delays in central conduction time were not directly correlated with hypoxia levels.